The COVID-19 outbreak in Beijing has spread to at least three provinces on the Chinese mainland, the National Health Commission said on Tuesday.

At least seven people linked to cold storage operations in the Fengtai district contracted COVID-19 and were identified after returning to Hebei, Shandong and Shanxi provinces to spend the Lunar New Year holiday.

The patients included a pregnant woman and two long-distance truck drivers, a statement released by the commission said.

According to the Hebei Health Commission, the northern province reported three new COVID-19 patients on Sunday. All are workers who returned Xiongan New Area from a cold storage operation in Fengtai district last week.

In Shanxi province, a pregnant woman who once worked at a cold storage operation in Fengtai district was confirmed positive when she returned home to Datong city on Sunday.

Two long-distance truck drivers tested positive when they returned to Jinan, Shandong province, from Fengtai district on Thursday. The pair are close contacts of confirmed cases detected in Fengtai, the Shandong Health Commission said on Tuesday.

Also, a person who returned to Liaocheng from a cold storage operation in Fengtai district was also confirmed with COVID-19 on Sunday.

On Monday, Pang Xinghuo, deputy director of the Beijing Municipal Center for Disease Control and Prevention, said the outbreak in Fengtai is controllable because the source of the Delta strain involved has been identified and the transmission chain is basically clear.

Contact the writer at zhengcaixiong@chinadaily.com.cn